A user may wish to use a frequency that is unlicensed for broadcast television for communication, for a wireless local area network (LAN) or for communication with other users. For example, the user may wish to use a white space channel (e.g., an unused channel in the spectrum that is allocated for television broadcasting), for communication. However, two or more devices may autonomously select the same white space channel from among a plurality of available white space channels. This will create interference between various users of such white space channels, e.g., if these users want to use the available white space channels for their own purposes such as operating a wireless LAN by each user.
Additionally, if two or more devices actually want to communicate with each other via a white space channel, another problem arises where the two or more devices actually communicate with each other before they can be certain that they have found a vacant white space channel. One approach is to implement an initial negotiation between the various devices for the purpose of identifying an available white space channel. Unfortunately, the signals transmitted for the initial negotiation for the purpose of identifying a white space channel available may cause interference with television broadcasts. For example, if a channel is un-licensed at a first location of a first device, but is a licensed channel at the second location of a second device, then when the first device operating under the assumption that the channel is unlicensed, uses the channel to communicate with the second device, the transmitted signal will potentially cause interference with a television broadcast at the second location of the second device.